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Call for ContributionsHETEROCYCLES Special Issue Vol. 99 in honor of Professor Tohru Fukuyama on 70th Birthday

Submission deadline: September 10, 2018
On the occasion of Professor Tohru Fukuyama's 70th birthday, HETEROCYCLES editorial office is planning to publish special anniversary issue on April 1, 2019 as Vol. 99. Authors are invited to submit their work to this topical issue.
Authors wishing to submit their manuscript should contact editorial office via e-mail by the end of May, 2018. Manuscript should reach the editorial office no later than September 10, 2018.
Contact: submit@heterocycles.com

March 5, 2018

Heterocycles Award
HETEROCYCLES is pleased to announce Heterocycles Award.
In recognition of an outstanding oral presentation at the 47th Congress of Heterocyclic ChemistrySee more

December 13, 2017

Call for ContributionsHETEROCYCLES Special Issue Vol. 97 in honor of Professor Kiyoshi Tomioka on 70th Birthday

Submission deadline: February 15, 2018
On the occasion of Professor Kiyoshi Tomioka's 70th birthday, HETEROCYCLES editorial office is planning to publish special anniversary issue on September 1, 2018 as Vol. 97. Authors are invited to submit their work to this topical issue.
Authors wishing to submit their manuscript should contact editorial office via e-mail by the end of November, 2017. Manuscript should reach the editorial office no later than February 15, 2018.
Contact: submit@heterocycles.com

Abstract

Cyclization of 3-benzoyl-2-cyanobutyronitrile to 2-amino-4-methyl-5-phenylfuran-3-carbonitrile was effected under acidic conditions, rather than the basic conditions previously reported. Since treatment with trifluoroacetic acid (TFA) at room temperature is very mild, 2-amino-4-methyl-5-phenylfuran-3-carbonitriles containing various functional groups can be accessed via this route.

Abstract

The mannopeptimycins comprise a novel series of glycopeptide antibiotics that display activity against susceptible and resistant forms of gram-positive bacteria. Low isolated yields of these products from fermentation make the synthesis of easily accessible analogs attractive. A simplified hexapeptide is synthesized using a combination of solid-phase and solution-phase techniques.

Abstract

Base-mediated condensation reaction of 2,7-dibromotropone with 3,6,12,15-tetraoxa-9-thiaheptadecane-1,17-dithiol afforded 1:1 and 2:2 condensates (4 and 5). Troponoid trithiocrown ether (4) was used as a carrier through a chloroform liquid membrane. However, the guest selectivity of 4 was lower than that of the corresponding dithiocrown ether derivative (1e).

Abstract

The reaction of anthracene-9,10-carboaldehyde with various Grignard reagents under ambient conditions gave 9,10-bis(1-hydroxyalkyl)anthracene-9,10-peroxides and 9,10-anthraquinone as the first example. The endoperoxidation of 9,10-bis(1-hydroxyalkyl)anthracenes was assisted by the lone paired electron of oxygen in the side chain, and the endoperoxides were transformed to anthraquinone by the Grignard reagents.

Abstract

Aldol reactions of the lithium enolate of N-(4-methoxybenzyloxy)azetidin-2-one (1) were examined. High diastereoselectivity favoring the anti adduct was observed with achiral aldehydes. Modest α-stereocontrol with chiral aldehydes was realized. Application of this method for the efficient synthesis of novel β-amino esters is also described.

■ Synthesis in the Plakortone Series: Plakortone E

Patricia Y. Hayes and William Kitching*

*Department of Chemistry, School of Molecular and Microbial Sciences, The University of Queensland, St. Lucia, Brisbane, Queensland 4072, Australia

Abstract

A Pd(II)-mediated hydroxycyclisation-carbonylation-lactonisation sequence has operated efficiently with racemic enediol (8) to furnish (four) separable diastereomers of the bicyclic lactone system assigned to the sponge-derived, bioactive plakortone E. All four are cis ring-fused, and one is identical, on the basis of 1H and 13C NMR spectroscopic comparisons, with plakortone E, thus confirming its constitution and relative stereochemistry about the bicyclic lactone core. This synthetic approach, when applied to stereoisomer (13), will establish the absolute stereochemistry of plakortone E, likely to be that shown for (14).

■ A Unified Approach to the Enantioselective Synthesis of 2,6-cis and trans Disubstituted Tetrahydropyranones

Michael T. Crimmins,* Caroline J. Diaz, and Kyle A. Emmitte

*Department of Chemistry, University of North Carolina, Chapel Hill, NC 27599-3290, U.S.A.

Abstract

A stereoselective construction of cis- and trans-2,6-disubstituted tetrahydropyranones, based on strategy which combines an asymmetric alkylation and ring closing metathesis for the formation of a cyclic enol ether, is reported.

■ A Stereocontrolled Synthesis of Hapalosin

Abstract

A facile synthetic method for two components of hapalosin, that is, β-hydroxy-γ-amino acid and β-hydroxy acid, has been established by utilizing chiral building blocks efficiently resolved in a lipase-catalyzed transesterification. Furthermore, the synthesis of hapalosin through macrolactamization of the seco acid derived from these two components and (S)-2-hydroxy-3-methylbutyric acid has thus been demonstrated.

Abstract

A synthetic route to pharmaceutically important tricyclic pyrrolopyrimidines was developed. The method employs a palladium-mediated Heck cyclization as the critical step in the construction of the final six membered ring.

■ Synthesis of 2-Arylbenzothiazoles from 2-Aminobenzenethiol and Aryl Aldehydes Catalyzed by Scandium Triflate

Abstract

2-Aminobenzenethiol and an aryl aldehyde reacted to give a benzothiazoline via an imine intermediate, and the benzothiazoline was aromatized by oxygen or hydrogen peroxide to give a high yield of 2-arylbenzothiazole in the presence of a catalytic amount of scandium triflate Sc(OTf)3. The intermediary benzothiazoline was isolated and allowed to react with O2 or H2O2 in the presence of Sc(OTf)3, and the Lewis acid was found to also catalyze the oxidative process other than the ring closing step.

Abstract

A new class of potent inhibitors of dipeptidyl peptidase IV (DP-IV) for the treatment of type II diabetes are described. Presented herein is the synthesis of indole-fused and thiazole-fused cyclohexylglycines. Pyrrolidine-derived amides of these novel heterocycles led to the discovery of thiazole derivatives (3f) and (11a), both low nanomolar inhibitors of DP-IV (IC50 = 6 nM).

■ Synthesis of New Potentially Antiviral Furan-fused Compounds by Thermolysis of Benzocyclobutene Derivatives

Abstract

New potentially antiviral furan-fused tetracyclic compounds were prepared using intramolecular cycloaddition of o-quinodimethane generated by thermolysis of benzocyclobutene derivatives. It was found that the reaction course was changed depending on the length of alkyl chain connecting quinodimethane and furan ring.

■ Photo-induced C-C Bond Formation of 1,3-Dimethylthymine and Its Related Compounds with Naphthalene

Abstract

UV-Irradiation of 1,3-dimethylthymine (1a) and naphthalene (2) resulted in C-C bond formation through 1,4-cycloaddition to give cis-ethenobenzoquinazoline (3) in high stereoselectivity and in fair yield. Similar irradiation of 1,3-dimethyluracil and its derivatives with a substituent at C-5 underwent cycloaddition to give the corresponding barrelene derivatives in fair yields.

■ A Uniquely Accessible Route to the Diastereoselective Synthesis of Azetine Derivatives

Abstract

In the diastereoselective additions of chlorotitanium enolate of N-propionylthiazolidine-2-thione (2) to nitriles via the corresponding N-metalloaldimines (Al, B, Zr as metals), thiazolidine-2-thioneazetines (3) are preferentially formed over the dihydropyrimidinones (4), with the ratios of compounds (3/4) ranging from 5:1 to 17:1 (for R = phenyl, 1-naphthyl and 2-thienyl).

■ Preferential Conformation of the Six-membered Cyclic Compounds Bearing Both Trimethylsiloxy(or Methoxymethyleneoxy) and Tributylstannyl Groups at the Geminal Position

Abstract

The preferential conformer and conformer ratio in the cyclohexane, oxane, and thiane derivatives bearing both trimethylsiloxy (or methoxymethyleneoxy) and tributylstannyl groups at the geminal position were determined on the basis of their 3J(119Sn-13C) coupling constants and 13C NMR spectral analyses at low temperature.

Abstract

The ab initio MO calculations with HF/6-31G* basis set were performed in the neutral 5H,7H-dibenzo[b,g][1,5]dithiocin 12-oxide (1), the mono-protonated (1-H+) and the di-protonated (1-2H+) sulfoxides. The calculations indicated that the protonation is very important process for the 1,5-oxygen shift and the oxygen atom approaches to another sulfur by protonation. The inside oxygen conformation (the TBi or the BBi) is important for the intramolecular oxygen shift to form the oxygen-bridged intermediate in 1-2H+-BBb, and the outside oxygen conformation (the TBo or the BBo) is the most probable conformation to form the sulfurane intermediate in 1-2H+-BBo and 2-2H+-BBo, respectively.

Abstract

Stereoselectivitywas investigated in the epoxidation of (-)-8-phenylmenthyl E-3-aryl-2-phosphonoacrylates (2a-d) with hydrogen peroxide and potassium carbonate to give the corresponding epoxides (3a-d). The reaction of the E-isomeres gave the corresponding trans-epoxy derivatives with the moderately higher diastereoselectivity as the major diastereomers as compared with that of the cis isomers.

Abstract

A new method to synthesize cyclic sulfoxide derivatives was developed utilizing Pd-catalyzed sulfinylzincation, which proceeds with high syn-selectivity under mild conditions. The resulting vinylzinc species reacted with electrophiles such as proton, allyl bromide, and benzoyl chloride to afford a single geometric isomer.

Abstract

Six new cage-annulated azacrown ethers (1 - 6) have been prepared, and their respective abilities to function as alkali metal cation and/or heavy metal cation complexants have been assessed via application of electrospray ionization mass spectrometry (ESI-MS) techniques. All of these host systems bind to H+; however, they also generally display a high degree of selectivity toward complexation with Ag+.

*School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan

Abstract

Stereoselective ring transformation of 2-vinylheterocycles to vinylcarbocycles was efficiently carried out by the use of a zirconocene equivalent (“Cp2Zr”). The transformation proceeded through an intramolecular allylation of Z-allylic zirconocene species to the epoxide or aziridine ring.

■ Oxidative Addition of Chloro- and Dichloroacetic Acid to Alkenes to Give α-Chloro- and α,α-Dichlorobutyrolactones with Manganese(III) Acetate

Abstract

Oxidative addition of chloroacetic acid and dichloroacetic acid to alkenes with Mn(OAc)3 to give α-chloro- and α,α-dichlorobutyrolactones proceeds in moderate to good yield in MeCN containing one equivalent of the sodium salt of the carboxylic acid.